Minimal is an entirely different property to backwards compatibility.
motherfuckingwebsite.com is more minimal and usable than these frameworks.
For a long time we were forced to use the ugliest hacks imaginable to get to the nice (responsive, design-minimalist(!)) layouts we wanted, because CSS layout tools were utter archaic bs, for years on end, because browsers iterated so slowly.
Then things started speeding up, and we're getting to make better websites (and apps!) that are way easier to design (with the correct design theory equivalents), implenent (with less code) and easier to maintain (i.e., understand). And you're not missing out if you just keep your browser up to date.
I know it sucks if you're on an unsupported device that doesn't get any updates, fair.
But let's face it: 99% of the population is better off security-wise when we're not enabling them to run unpatched devices forever.
Much of the issues of layout were already solved more than 12 yrs back, ie when css3 became mainstream.
The issue is devs are unaware about different levels of css3 or just plain ignorant about it.
Are you aware about the different levels of css3? Are you even aware there are levels to css3? Why are these frameworks not listing them and simply saying that they comply with web standards? Which specific web standards do they comply?
Any new css3 feature should have a fallback if they say they comply to web standards, which these frameworks don’t add.
Basically you want to adopt latest w3c guideline but completely ignore wcag guidelines on accessibility - https://www.thewcag.com/principles/robust
Why should some population forced to suffer because of your ignorance. I am sorry if I am blunt, but your comment about polarising users is rude.
Which comes back to my main point, Devs are simply not educating themselves about the fundamentals of web design.
There are older browsers which still get security patches?
ios updates unfortunately ties everything to a single batch. Unlike android. I have an older blackberry, that still gets latest app updates.
What is even hilarious is ads render with pixel perfection on older devices. So for some reason, ad networks care about browser compatibility than devs putting the same ads on their incompatible website.
And yes, it makes sense to use one particular old browser as a general proxy for older browsers in general, so people shouldn't get hung up on the particular version of Safari you happened to mention.